In a series production of refrigerating systems, such as refrigerators or air conditioning systems, it is desirable to integrate a leak test at atmospheric pressure into the series production. Here, it is a particular difficulty that extremely low refrigerant concentrations in the ppb range have to be detected within a very short time span of several 10 seconds. Other gas-emitting hydrocarbons, such as those emitted by paints, solvents, lubricants or detergents, may create a disturbing background that must be eliminated by a corresponding selective measurement of the refrigerant. A bubble test in the context of an immersion test is hardly practicable, since irreversible damage to the apparatus under test may occur.
Currently, there is no technique with which a fully functional refrigerating system could integrally be checked for refrigerant leakage in a short time span in keeping with the cycle of a manufacturing line. In a makeshift approach the sites known as potential leak, such as soldering points, seals, valves and the like, are checked locally using a sniffer. This puts an extreme demand on the operator's care and attention.